PROJECT SUMMARY More than 700,000 total knee arthroplasty (TKA) surgeries are performed annually in the United States, with projections of 3.5 million performed annually by 2030. While recent advances have led to improved TKA rehabilitation, the persistence of atypical movement patterns after unilateral TKA?characterized by surgical knee disuse?remains a major problem. Importantly, these atypical movement patterns are associated with persistent quadriceps weakness and poor physical function. In addition, atypical movement patterns create compensatory increased loading on the contralateral knee, which may be linked to progression of contralateral knee osteoarthritis. Coupling contemporary progressive strengthening with innovative strategies emphasizing motor learning principles to remediate atypical movement patterns has the potential of advancing rehabilitation to improve movement pattern quality and overall functional recovery after unilateral TKA. Therefore, the overall aim of this investigation is to perform a randomized controlled trial to determine if the addition of a novel movement pattern training program (MOVE) to contemporary progressive rehabilitation improves functional movement pattern quality more than contemporary progressive rehabilitation alone (CONTROL) after unilateral TKA. Both the MOVE and CONTROL interventions will be delivered in an outpatient physical therapy setting. Testing will occur pre-operatively and after TKA at: 2 months (end of intervention), 6 months (primary endpoint), and 2 years. The primary outcome will be change in peak surgical knee extension moment from baseline to 6 months following TKA. Peak knee extension moment will be calculated with 3-dimensional instrumented motion analysis during participants walking, rising from a chair, and stair stepping. The secondary goal is to determine if movement pattern training improves performance-based and self-report measures physical function, and lessens contralateral knee OA progression. We expect the MOVE program will result in substantial improvements in surgical knee extension moments compared to the CONTROL program, and that these improvements will be associated with improved physical function. Similarly, we expect that greater symmetry in peak knee extension moments will be correlated with less progression of contralateral knee OA. Finally, an exploratory aim will evaluate how knee joint forces relate to contralateral knee OA progression over time.